An automotive vehicle brake unit of this kind is, for example, known from the earlier patent application No. P 38 17 785.4 of the applicant. The particular feature of this prior-art brake unit consists in that it is furnished with pneumatic means which in the event of a slip control action render it possible to aerate the first power chamber and/or to evacuate the second power chamber in order to activate, respectively to inactivate the boosting power of the vacuum brake power booster in a direction opposed to the actuating apparatus of the master brake cylinder.
The brake pedal pulsating along in the event of a control action is felt to be of disadvantage in the prior-art brake unit. It is considered a further disadvantage that the second power chamber of the vacuum brake power booster requires to be evacuated in order to completely cancel the hydraulic pressure existing in the master brake cylinder, so that the vacuum requirements become comparatively large.